ASCEND Study to Evaluate the Effectiveness of TYSABRI®
(natalizumab) as a Treatment for Secondary-Progressive Multiple Sclerosis

January 26, 2012 08:00 AM Eastern Standard Time

WESTON, Mass. & DUBLIN--(BUSINESS WIRE)--Biogen
Idec (NASDAQ: BIIB) and Elan
Corporation, plc (NYSE: ELN) today announced a global Phase 3b study,
ASCEND, that is being conducted to evaluate the effectiveness of TYSABRI
as a treatment for secondary-progressive multiple sclerosis (SPMS).
According to the National Multiple Sclerosis Society, approximately half
of all people initially diagnosed with relapsing-remitting multiple
sclerosis (RRMS) - the most common form of multiple sclerosis (MS) -
will transition to SPMS within 19 years.

Patients with RRMS typically experience unpredictable relapses; the time
between relapses is characterized by full or partial recovery and a lack
of disease progression. SPMS is characterized by a steady progression of
nerve damage, symptoms and disability, but the exact reasons for the
progression are unknown. The potential for greater disease burden in
SPMS typically includes decreased mobility, impaired activities of daily
living, loss of independence and reduced quality of life.

"There are limited treatment options available to people living with
SPMS and there is a high unmet need for effective therapies,” said Aaron
Miller, M.D., member of the ASCEND advisory board; Medical Director,
Corinne Goldsmith Dickinson Center for Multiple Sclerosis; and
Co-Director of the Multiple Sclerosis Care Center at Maimonides Medical
Center in Brooklyn, New York. “The ASCEND trial is investigating whether
treatment with TYSABRI may prevent worsening in walking, hand movement
and daily functioning in these patients.”

"One hypothesis behind the development of SPMS is that disease
progression is a result of chronic inflammation in the brain tissue
trapped behind the blood-brain-barrier. This causes destruction of the
myelin sheath which protects the coating around nerve fibers, as well as
the progressive loss of nerve cells, which can lead to disability in MS
patients,” said Professor Richard Reynolds, Professor of Cellular
Neuroscience, Imperial College, London; and Scientific Director of the
UK Multiple Sclerosis Society Tissue Bank. “Preliminary data suggest
that TYSABRI may hinder this inflammation in the brain and reduce
SPMS-related disease progression; therefore, further investigation of
this hypothesis is warranted."

The ASCEND study is part of the ongoing commitment of both Biogen Idec
and Elan to find ways to improve the well-being of patients with
multiple sclerosis.

About the ASCEND Study

ASCEND (AStudy
to Characterize the Efficacy
of Natalizumab on Disability
in SPMS) is a double-blind, placebo-controlled study with SPMS patients
being randomized to receive either TYSABRI 300 mg or placebo
intravenously every four weeks for 96 weeks. A global study, ASCEND is
expected to enroll approximately 850 patients in 15 countries.

Study participants will be between the ages of 18 and 58, inclusive,
with a diagnosis of SPMS for at least two years; an Expanded Disability
Status Scale (EDSS) score between 3.0 and 6.5, inclusive; MS Severity
Score of 4 or higher; documented, confirmed evidence of disease
progression, independent of clinical relapses during the one-year prior
to enrollment; and naïve to TYSABRI treatment.

The primary endpoint is to investigate whether treatment with TYSABRI
slows the accumulation of disability not related to relapses in subjects
with SPMS.

Secondary endpoints are:

The proportion of subjects with consistent improvement in Timed
25-foot Walk (T25FW);

The change in subject-reported ambulatory status as measured by the
12-Item MS Walking Scale (MSWS-12);

The change in manual ability based on the ABILHAND questionnaire;

The impact of TYSABRI on subject-reported quality of life using the
Multiple Sclerosis Impact Scale-29 Physical (MSIS-29 Physical);

The change in whole brain volume between the end of study and week 24
using MRI; and

The proportion of subjects experiencing progression of disability as
measured by individual physical EDSS system scores.

TYSABRI is approved in more than 65 countries. TYSABRI is approved in
the United States as a monotherapy for relapsing forms of MS, generally
for patients who have had an inadequate response to, or are unable to
tolerate, an alternative MS therapy. In the European Union, it is
approved for highly active relapsing-remitting MS (RRMS) in adult
patients who have failed to respond to beta interferon or have rapidly
evolving, severe RRMS.

TYSABRI has advanced the treatment of MS patients with its established
efficacy. Data from the Phase 3 AFFIRM trial, which was published in the New
England Journal of Medicine, showed that after two years, TYSABRI
treatment led to a 68 percent relative reduction (p<0.001) in the
annualized relapse rate when compared with placebo and reduced the
relative risk of disability progression by 42-54 percent (p<0.001).

TYSABRI increases the risk of progressive multifocal leukoencephalopathy
(PML), an opportunistic viral infection of the brain which usually leads
to death or severe disability. Infection by the JC virus (JCV) is
required for the development of PML and patients who are anti-JCV
antibody positive have a higher risk of developing PML. Factors that
increase the risk of PML are presence of anti-JCV antibodies, prior
immunosuppressant use, and longer TYSABRI treatment duration. Patients
who have all three risk factors have the highest risk of developing PML.
Other serious adverse events that have occurred in TYSABRI-treated
patients include hypersensitivity reactions (e.g., anaphylaxis) and
infections, including opportunistic and other atypical infections.
Clinically significant liver injury has also been reported in the
post-marketing setting. A list of adverse events can be found in the
full TYSABRI product labeling for each country where it is approved.

TYSABRI is marketed and distributed by Biogen Idec Inc. and Elan
Corporation, plc. For full prescribing information and more information
about TYSABRI, please visit www.biogenidec.com
or www.elan.com.

About Biogen Idec

Through cutting-edge science and medicine, Biogen Idec discovers,
develops and delivers to patients worldwide innovative therapies for the
treatment of neurodegenerative diseases, hemophilia and autoimmune
disorders. Founded in 1978, Biogen Idec is the world's oldest
independent biotechnology company. Patients worldwide benefit from its
leading multiple sclerosis therapies, and the company generates nearly
$5 billion in annual revenues. For product labeling, press releases and
additional information about the company, please visit www.biogenidec.com.

About Elan

Elan Corporation, plc is a neuroscience-focused biotechnology company
committed to making a difference in the lives of patients and their
families by dedicating itself to bringing innovations in science to fill
significant unmet medical needs that continue to exist around the world.
Elan shares trade on the New York and Irish Stock Exchanges. For
additional information about Elan, please visit www.elan.com.

Safe Harbor

This press release contains forward-looking statements, including
statements about the development of TYSABRI in SPMS. These
forward-looking statements may be accompanied by such words as
"anticipate," "believe," "estimate," "expect," "forecast," "intend,"
"may," "plan," "will" and other words and terms of similar meaning. You
should not place undue reliance on these statements. These statements
involve risks and uncertainties that could cause actual results to
differ materially from those reflected in such statements, including the
risk that we may not fully enroll our planned clinical trials, the
occurrence of adverse safety events, regulatory authorities may require
additional information, further studies, or may fail to grant the
desired drug approval, or we may encounter other unexpected hurdles.
Additional risks and uncertainties are described in the Risk Factors
section of our reports on Form 10-K, Form 10-Q, Form 20-F and Form 6-K
and in other reports we file with the SEC. These statements are based on
our current beliefs and expectations and speak only as of the date of
this press release. We do not undertake any obligation to publicly
update any forward-looking statements.